CSMA/CA

Carrier Sensing Multiple Access / Collision Avoidance

This is the medium access control method employed in IEEE802.11 wireless networks. The IEEE 802.11utilizes collision avoidance rather than collision detection which is used in wired systems such as IEEE802.3 and Ethernet. Unlike these conventional wired networks, a WLANStation cannot detect a collision while transmitting as it operates in half duplex. If a collision occurs, the transmitting Station will not receive an acknowledgement from the intended receive Station. For this reason, acknowledgement packets have a higher priority than all other network traffic. Once all data transmission has been completed, the receive Station will transmit an acknowledgement before any other node can begin transmitting a new data packet. All other Stations must then wait for a longer period of time before they may begin transmission.